As its many definitions illustrate, a line can be many things: a long mark made on a surface; a row of letters; words spoken by an actor; a transportation company; and a course of action, to name a few. A visit to Gallery A3’s current show, “LINE|EDGE,” shows that a line comes in a variety of visual forms as well, so many in fact that it almost defies definition.

The exhibit, on view at the 28 Amity St. gallery in Amherst through July 27, features mostly abstract works by member artists Marianne Connolly, Helena Dooley, Constance Hamilton, Keith Hollingworth, Margaret Jean, Sue Katz, Tom Morton and Janet Wallerstein Winston. They explore a line’s many-sidedness in several media, including oil and acrylic paintings, woodcuts, encaustic sculpture, photography and a mix of artistic techniques.

As the show’s name suggests, a line can also be an edge, marking both an end and a beginning, a connector that leads from one place, idea or expression to another. With that in mind, each artist has on view two or three pieces that portray a visual journey tracing a line’s evolution.

In a pair of oil paintings on paper called “Morning Fields,” Hamilton suggests two cornfields set aglow by the rays of the early morning sun. In each, loose brush strokes of school-bus-yellow paint define the field’s contours, while its boundary — its edge — is a thin red line.

Hamilton explores the concept of edge, of the line as a boundary between two planes, by cutting a rectangular section from the paper canvas of one painting and splicing it onto the other, combining the images of both paintings. In each, the sections are joined together with tape, creating images that are alive with the dynamic tension of placing two once-disconnected pieces together.

Hollingworth’s two pieces, “By the Sea V” and “By the Sea VI” use line to examine the intersection between the universal /infinite and the terrestrial/finite. His paintings depict circles, deep blue orbs that seem to spin against a lighter blue sky. They suggest the still immensity of the ocean, the unfathomable deepness of space. Both paintings are bisected by lines, strands of rope attached to the top of the rectangular canvases and from which are suspended conch shells. Suggesting plumb lines or pendulums, the rope/shell constructions introduce the concept of the everyday — the smell of the sea, the sound of the ocean and the feel of sand and water. The suspended conches are timelines, mankind’s attempt to measure life amid the immensity of the universe.

In “Spiraling Through,” Sue Katz’s mixed-media, wall-mounted sculpture, line is on the move. Four square wooden blocks stacked vertically are tied together with circular swirls of rusted wire. The blocks are decorated with encaustic — different colored clays that are burnt into the surface — in a range of colors from deep brown to white. A strand of wire runs from one block to the next, forming concentric circles on the surface of each. This line leads the eye from block to block, joining the work’s separate pieces into a whole and providing a whimsical counterpoint to the symmetry of the four rectangles.

Marianne Connolly’s two-piece work “Dorothy’s Window” also probes the nature of lines and edges. While it is a photograph — one of the pieces is a close-up of a section of the other — it looks like a painting, with soft yellows and greens overlaid with bold black lines. A close inspection, though, shows that the greens are foliage seen through a foggy window with yellow and black lines painted on its surface. At the upper right corner, a section of a house’s exterior siding can be seen.

Here the window pane through which we look doubles as a picture plane, appearing like the surface of a painting. The window is an edge that leads to the real three-dimensional space outside it and, at the same time, a plane that incorporates illusory space, created by the interplay of color and line.

The triangles and square in Winston’s “Structure II” bring to mind the precise pattern of architecture, the symmetrical designs that people use to decorate their surroundings. Juxtaposed against the rigid orderliness of these shapes, a thin black line wanders down one side of the work, like a meandering stream or a simple melody. This line suggests the role that the human imagination, capricious and unpredictable, plays in tying the geometric shapes together to form a unified whole.

Ultimately, “LINE|EDGE” does the same thing: It invites us to follow our own lines of thought, leading to the fresh insights often found in uncharted territory.